Doctor Who has its fair share of strong characters, especially since they can originate from just about anywhere (and anywhen) in space and time. The show's protagonist Time Lord, the Doctor, shows mental strength as he uses his intelligence and determination to battle foes. The Doctor's companions also have to possess courage and be quick-thinking in the face of danger.
Source：https://www.cbr.com/doctor-who-strongest-characters-ranked/
